High-pressure pump

ABSTRACT

A pump having pistons at opposite ends of the piston rod wherein the piston rod extends through a spool valve body separating the cylinders for the oppositely disposed pistons. A pilot valve body is mounted on the spool valve body and is responsive to reciprocation of the pistons. At the end of a piston stroke the pressure source connected to the pilot valve body is directed into the spool valve body into one of a pair of annular lands on the piston rod and back into an end chamber for the pilot valve element thereby moving the pilot valve element to the opposite end of the pilot valve body in turn reversing the flow of fluid from the pressure source into the piston chambers. At the end of each half cycle this procedure is sequentially followed. The pistons are pivotally connected to the piston rod about axes extending at 90* to each other to permit self-compensation for any misalignment that may exist in the pump structure. The reciprocation of the pilot valve element is dampened by bypassing part of the inlet fluid to the opposite end of the pilot valve element and the pilot valve element is releasably held at one end of the pilot valve body by a magnet.

Unite States atent George D. Conlee Humboldt, Iowa July 27, 1970 Nov. 23, 1971 Slifer Manufacturing Co., Inc. Humboldt, Iowa [72] Inventor [21] App]. No. [22] Filed [45] Patented [73] Assignee [54] HIGH-PRESSURE PUMP 10 Claims, 8 Drawing Figs.

[56] References Cited UNITED STATES PATENTS 2,799,444 7/1957 Schemmel 417/397 X 3,304,126 2/1967 Rupp et al. 91/275 X Primary Examiner-Robert M, Walker A11orneyZarley, McKee & Thomte ABSTRACT: A pump having pistons at opposite ends of the piston rod wherein the piston rod extends through a spool valve body separating the cylinders for the oppositely disposed pistons. A pilot valve body is mounted on the spool valve body and is responsive to reciprocation of the pistons. At the end of a piston stroke the pressure source connected to the pilot valve body is directed into the spool valve body into one ofa pair of annular lands on the piston rod and back into an end chamber for the pilot valve element thereby moving the pilot valve element to the opposite end of the pilot valve body in turn reversing the flow of fluid from the pressure source into the piston chambers. At the end of each half cycle this procedure is sequentially followed. The pistons are pivotally connected to the piston rod about axes extending at 90 to each other to permit self-compensation for any misalignment that may exist in the pump structure. The reciprocation of the pilot valve element is dampened by bypassing part of the inlet fluid to the opposite end of the pilot valve element and the pilot valve element is releasably held at one end of the pilot valve body by a magnet.

PATENTEIJunv 23 I97! 3', 622,250

sum 1 or 2 firramves s HIGH-PRESSURE PUMP The high-pressure pump of this invention will provide high pressures with little or no pulsation and operates with a minimum number of parts thereby requiring a minimum of maintenance. The pump is easily fabricated since reasonable tolerances may be maintained by having the pistons pivotally connected to the opposite ends of the piston rod about axes extending at 90 to each other thereby self-compensating for any misalignment in the pump structure.

The piston rod in the main pump assembly functions in a dual capacity as it includes annular longitudinally spaced apart lands which provide passageway communication with the pilot valve mounted on the spool valve body. The spool valve body additionally functions to hold together the cylinders extending in opposite directions and enclosing the pistons.

This invention consists in the construction, arrangements and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:

FIG. 1 is a fragmentary side elevational view of the highpressure pump of this invention including the pilot valve unit mounted on the spool valve body.

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1.

FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 1.

FIG. 5 is a fragmentary longitudinal cross-sectional view of the spool valve body showing the communication between the annular lands on the piston rod and the pilot valve which has been turned 90 for purposes of illustration.

FIG. 6 is a view similar to FIG. 5 but showing the piston in the pump having moved to the extreme right position and the valve element in the pilot valve having moved to the right in direct response thereto.

FIG. 7 is a view similar to the views in FIGS. 5 and 6 but only of the pilot valve showing the valve element moved completely to the right with the fluid flow directions being indicated; and

FIG. 8 is a fragmentary reduced in scale top plan view of the spool valve body taken along line 8-8 in FIG. 6.

The high-pressure pump of this invention is referred to in FIG. 1 generally by reference numeral 10 and includes a spool valve body 12 from which oppositely extending cylinders 14 and 16 are provided and held in place by end plates 20 having bolts 22 interconnecting the spool valve body 12 to the end plates 20.

A piston shaft 24 having a pair of pistons 26 and 28 at opposite ends is movable within the cylinders 14 and 16, each pair of pistons moving between the spool valve body 12 and the adjacent end plate 20.

A pilot valve body 30 is secured by bolts 32 on the top side of the spool valve body 12.

The piston rod 24 and its operation as a spool valve in the spool valve body 32 are best seen in FIGS. 5-8 wherein a pair of longitudinally spaced annular lands 34 and 36 are provided on opposite sides of a relatively larger in cross section piston rod portion 38. A trio of longitudinally spaced vertically oriented passageways 40, 42 and 44 extend closely adjacent the longitudinal center of the piston rod opening 46 in the spool valve body 12.

The hydraulic fluid is fed into and out of the fluid chambers 48 and 50 formed between the pistons 26 and the adjacent ends of the spool valve body 12 through a pair of passageways 54 and 56 which extend vertically in parallel relationship to the three passageways 40, 42 and 44. The passageways 54 and 56 communicate with the oppositely disposed fluid chambers 48 and 50 and the passageways are in communication with respective annular grooves 58 and 60 formed in the valve body 12.

The pilot valve body member 30 includes a longitudinally positioned central bore 62 in which a valve member 64 moves between end bolts 66 and 68. A fluid pressure source is in communication with a threaded inlet opening 70 while a discharge threaded opening 72 is provided on the opposite side thereof. It is appreciated that in FIGS. 5 and 6 the pilot valve body 30 has been rotated 90 degrees for purposes of illustration in relating the passageways between the spool valve body 12 and the pilot valve body 38.

The center passageway 42 of the passageways 40, 42 and 44, in the spool valve body 12 communicates with the inlet passageway 70 which in turn includes a passageway 74 in registry with passageway 42. An inlet chamber 76 around the valve portion 78 is provided as an extension of the inlet passageway 70. The opposite ends 80 and 82 of the valve element 64 are exposed in cavities 84 and 86 respectively which in turn are in direct communication with passageways 88 and 90 in registry with passageways 40 and 44 respectively in the spool valve body 12. The two passageways 54 and 56 in the valve body 12 are in registry with passageways 94 and 96 in communication with enlarged cavities 98 and 100 apart of the openings 62 for the valve element 64. On opposite sides of the valve portion 78 are annular lands 104 and 106.

Each of the chambers 84 and 86 include small bypass openings 108 and 110 placing them in communication with each other and with the outlet opening 72.

The end bolts 66 and 68 include on their inner ends at the longitudinal center axis of the valve element 64, permanent magnets and 122 for magnetic engagement with the valve end portions 80 and 82 respectively at the end of travel of the valve element in each direction to hold the valve element in place at the end of its travel until the next half cycle begins.

It is seen that the mounting bolts 32 extend through holes 124 in the pilot valve body 30.

Referring now to FIGS. 1, 3 and 4 it is seen that the pair of pistons 26 and 28 at opposite ends of the pump assembly are secured on the piston rod 24 by a spring pin extending through the pistons 26 but at 90 degrees to each other to provide a pivotal action between the piston units at opposite ends on the piston rod 24 to accomplish self-compensation for any misalignment that may occur in the construction and operation of the pump. It is important that the pivotal axes be at 90 degrees to each other to provide universal type swivel movement between the piston assemblies and the piston rod. The outer pistons 28 are rigidly connected to the inner pistons 26 by star-shaped in cross section shafts as seen in FIG. 4. A pair of seals I42 and 144 are provided on the outer end of the piston 28 to separate the material chamber 146 from the hydraulic fluid chamber 50 and the dead space chamber 148 between the pistons 26 and 28. Should any of the material being pumped in the chamber 146 or the hydraulic fluid in the chamber 50 bypass either of the pistons 26 or 28 it will pass through an exhaust bleed port disposed between the piston 26 and 28 such that neither piston passes over the exhaust bleed port. A pair of spring biased inlet and outlet ball valves and 172 are provided in the end plates 20 for communication with the material chamber 146 and may be connected to a high-pressure type cleaning unit or the like.

In operation of the high-pressure pump of this invention it is seen that an appropriate hydraulic pump is connected to the inlet 70 of the pilot valve 30 with an outlet conduit being connected to the outlet passageway 72. Appropriate working conduits are connected to the material chambers 146 on the pump by utilizing the pressure valve 170 and 172 in the end plates 20.

The sequence of operation is seen best in FIGS. 5, 6 and 7 again noting that the pilot valve body 30 has been rotated 90 for purposes of illustrating the flow of fluids between the pilot valve 30 and the spool valve 12. As the piston rod 24 moves to the right as seen in FIG. 5, the fluid is leaving the fluid chamber 48 under the pressure of the left-hand piston 26 and is exhausted through the passageway 54 (FIG. 8) into the cavity 98 in the pilot valve 30 and thence out past the land 104 to the annular land 36 the outlet opening 72 as indicated by the arrows 180 in H6. 5. At the same time, oil is entering the right-hand pump chamber 50 by passing down through the passageway 96 in the pilot valve 30 after entering the cavity 1% from the inlet passageway 70 past the valve portion 78 around the annular land 106. When the pistons are intermediate their ends of travel the piston rod portion 38 between the annular lands 34 and 36 basically closes oif the passageways 40, 42 and 44.

As now seen in H6. 6, the pistons have moved completely to the right placing the passageways 40 and 42 in communication with a cavity 1186 around the annular land 34 thereby allowing fluid to pass from the inlet opening 70 of the pilot valve into the spool valve through passageway 42 and back up through passageway 40 into passageway 88 in the pilot valve and into the chamber 84 where the fluid pressures bear against the valve end portion 80 as indicated by the arrows 1190 thereby causing the valve element 64 to begin to move to the right closing off communication between the passageway 96 in the pilot valve and passageway 44 in the spool valve. The pilot valve then moves to the position of FIG. 7 fully to the righthand position opening up the communication between the passageway 94 and the inlet 70 through the passageway 94 in communication with the cavity 98 around the annular land 104. At this time the spool valve passageway 56 is open to communication with the pilot valve passageway 96 for discharging fluid from the right-hand side fluid compartment chamber 50 to the outlet opening 72 in the pilot valve. Upon the pistons moving to the extreme left-hand position the reversing procedure will occur in a similar manner utilizing which will provide communication between passageways 42 and 44 to return the pilot valve element 64 to its left-hand position as seen in FIG. 5.

As the pilot valve element 64 moves back and forth it is cushioned by bypass fluid flowing through the passages 108 and 110 as indicated by the arrows in FIG. 6 and once the valve element 64 has bottomed out at the end of its travel in one direction magnets 120 or 122 may maintain the valve element in position preventing it from rebounding oh the encb of the valve body.

The provision of pivoting the pistons through spring pins 130 to the opposite ends of the piston shaft 24 and providing the pivotal axis at 90 degrees to each other assures that slight misalignment in the pump will not damage component parts during operation and particularly will allow the piston rod doubling as a spool valve to function accurately and within close tolerances as required.

1 claim:

1. A pump comprising,

a housing,

a piston rod having pistons on its opposite ends in said housa spool valve body positioned between said pistons and having a bore extending therethrough in which said piston rod is moveably received, said spool valve body having two passageways adapted to be placed in communication with fluid chambers formed in said housing between said pistons and said valve body, said spool valve body having three pilot valve passageways said piston rod having longitudinally spaced apart annular lands adapted to alternately place one of said three passageways in communication with one of the other three passageways and the portion of said piston rod between said annular lands being relatively larger in cross section than said lands and adapted to alternately close one of said other three passageways as said pistons move back and forth to the end of each stroke in said housing,

a pilot valve body having a moveable valve element and inlet and outlet openings adapted to be connected to a source of fluid under pressure, i

said pilot valve element having valve portions adapted to alternately open and close communication between said inlet and outlet openings and said two fluid passageways upon bein moved between first and second positions, at the end 0 each stroke of said piston rod one of said three passageways being in communication with said pilot inlet opening and adapted to alternatively place one of said other three passageways in communication through one of said annular lands on said piston rod with the ends of said pilot valve element to move said pilotwalve element from the end of a stroke to a first center position operatively closing both fluid passageways to communication with said inlet and outlet openings, and to a second end of stroke position operatively opening one of said fluid passageways and closing the other fluid passageways communication with said inlet opening and opening the other fluid passageway to said outlet opening and closing said one fluid passageway to said outlet opening thereby alternatively introducing fluid into one of said fluid chambers and discharging it from the other fluid chamber.

2. The structure of claim 1 wherein said pistons are pivotally connected to said piston rod thereby allowing the pistons throughout each stroke to follow the interior contour of said housing and not bind.

3. The structure of claim 2 wherein said pivotal axes at opposite ends of said piston rod extend at to each other.

4. The structure of claim 1 wherein said pilot valve body includes a magnet at each end for releaseably holding said valve element alternatively at the end of each stroke in opposite directions.

5. The structure of claim 1 wherein said three pilot valve passageways are positioned in a plane parallel to the longitudinal axis of said piston rod.

6. The structure of claim 5 wherein said two fluid passageways are laterally offset from the longitudinal axis of said piston rod.

7. The structure of claim 5 wherein said one passageway of said three passageways is the center passageway of the three passageways and said other two passageways are in a communication with end chambers for said pilot valve element in said pilot valve body.

8. The structure of claim 7 wherein said pilot valve body includes a dampening passageway connecting said end chambers whereby upon said pilot valve element being moved by fluid pressure from said inlet opening a portion of said fluid will be bypassed to the other end chamber to cushion the movement of said pilot valve element as it moves into said otherendchamber. v

9. The structure of claim 8 wherein said housing includes said spool valve body engaged at opposite ends by oppositely extending piston cylinders.

10. The structure of claim 9 wherein said pilot valve body is rigidly secured on the exterior of said spool valve body. 

1. A pump comprising, a housing, a piston rod having pistons on its opposite ends in said housing, a spool valve body positioned between said pistons and having a bore extending therethrough in which said piston rod is moveably received, said spool valve body having two passageways adapted to be placed in communication with fluid chambers formed in said housing between said pistons and said valve body, said spool valve body having three pilot valve passageways said piston rod having longitudinally spaced apart annular lands adapted to alternately place one of said three passageways in communication with one of the other three passageways and the portion of said piston rod between said annular lands being relatively larger in cross section than said lands and adapted to alternately close one of said other three passageways as said pistons move back and forth to the end of each stroke in said housing, a pilot valve body having a moveable valve element and inlet and outlet openings adapted to be connected to a source of fluid under pressure, said pilot valve element having valve portions adapted to alternately open and close communication between said inlet and outlet openings and said two fluid passageways upon being moved between first and second positions, at the end of each stroke of said piston rod one of said three passageways being in communication with said pilot inlet opening and adapted to alternatively place one of said other three passageways in communication through one of said annular lands on said piston rod with the ends of said pilot valve element to move said pilot valve element from the end of a stroke to a first center position operatively closing both fluid passageways to communication with said inlet and outlet openings, and to a second end of stroke position operatively opening one of said fluid passageways and closing the other fluid passageways communication with said inlet opening and opening the other fluid passageway to said outlet opening and closing said one fluid passageway to said outlet opening thereby alternatively introducing fluid into one of said fluid chambers and discharging it from the other fluid chamber.
 2. The structure of claim 1 wherein said pistons are pivotally connected to said piston rod thereby allowing the pistons throughout each stroke to follow the interior contour of said housing and not bind.
 3. The structure of claim 2 wherein said pivotal axes at opposite ends of said piston rod extend at 90* to each other.
 4. The structure of claim 1 wherein said pilot valve body includes a magnet at each end for releaseably holding said valve element alternatively at the end of each stroke in opposite directions.
 5. The structure of claim 1 wherein said three pilot valve passageways are positioned in a plane parallel to the longitudinal axis of said piston rod.
 6. The structure of claim 5 wherein said two fluid passageways are laterally offset from the longitudinal axis of said piston rod.
 7. The structure of claim 5 wherein said one passageway of said three passageways is the center passageway of the three passageways and said other two passageways are in a communication with end chambers for said pilot valve element in said pilot valve body.
 8. The structure of claim 7 wherein said pilot valve body includes a dampening passageway connecting said end chambers whereby upon said pilot valve element being moved by fluid pressure from said inlet opening a portion of said fluid will be bypassed to the other end chamber to cushion the movement of said pIlot valve element as it moves into said other end chamber.
 9. The structure of claim 8 wherein said housing includes said spool valve body engaged at opposite ends by oppositely extending piston cylinders.
 10. The structure of claim 9 wherein said pilot valve body is rigidly secured on the exterior of said spool valve body. 